Musnad Ahmad Hadith 15098

It is narrated from Jabir (may Allah be pleased with him) that once during the blessed era of the Prophet (ﷺ), there was a solar eclipse in intense heat. The Prophet (ﷺ) led his companions in a long prayer until people began to fall down. Then he performed a long bowing (ruku‘), then stood up for a long time after raising his head, then performed another long bowing, and then stood up for a long time after raising his head, then performed two prostrations. In the second rak‘ah, he did the same. Thus, there were four bowings and four prostrations in this prayer.